1. Field of the Invention
This invention generally relates to a rear derailleur hanger alignment tool for a bicycle that has a rear derailleur hanger for mounting a rear derailleur thereto.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Many bicycles use a rear derailleur to change gears. Typically, the rear derailleur is mounted to a rear derailleur hanger of the bicycle frame. Sometimes when the bicycle falls over, the rear derailleur hits the ground, which can bend the rear derailleur hanger of the bicycle frame inward towards the center of the bicycle. When the rear derailleur hanger of the bicycle frame is bent, this often results in poor shifting performance. Thus, tools have been proposed for determining misalignment of derailleur hanger. One example of such a tool is a derailleur hanger alignment gauge model DAG-1 that is sold by Park Tool USA. While this tool generally works well, this tool can be somewhat difficult to measure several points due to interference with a chain stay, a fender, a rack or other bicycle accessories. In particular, the chain stay, the fender, the rack or the other bicycle accessories may block the gauge from rotating to the various points for taking measurement. To solve this problem, the derailleur hanger alignment gauge is provided with O-rings that are used as markers so that the gauge can be moved to pass the obstacle, and then the gauge can be returned to its original position. However, this arrangement requires setting O-rings and then moving the gauge, which can result in errors.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved rear derailleur hanger alignment tool. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.